seismic design-10 miles length oil pipeline 9mult. support e

huangyhg

seismic design-10 miles length oil pipeline (mult. support e
hi:
we are in the process of analyzing a proposed fuel line to transport bunker c and diesel fuel from a dock to an existing tank facility.  both pipes (20 and 24") runs along the side way of an existing main road and they will have a series of overpass to overcome some creeks at the area.  approximately 80 percent of the pipeline will be located above ground from 3 to 6 feet in height and the other 20% will be buried around 48" below finish grade. this pipeline will be located on a seismic zone 3 and no active fault has been detected at the area after a preliminary seismic hazard analysis.
for this amount of pipe length, we are wondering if under a seismic event we have to consider a different approach as we normally proceed with a building or any other structure that has to comply with the regulatory design codes.  we are still designing under the ubc 97 and the question is as follows:
1) what decides if a special seismic analysis is required for this application:
   * pipeline length,
   * pipeline geometry and/or geography location,
   * api or any other code regulation,
   * nature and/or location of supports
2) is it strictly necessary to perform a multiple support excitation analysis?
3) how does any of these analysis could affect the stress analysis that is normally performed to this type of pipeline?